阅读说明：本技术 Y型分子筛及其制备方法 (Y-type molecular sieve and preparation method thereof ) 是由 庄立 罗一斌 欧阳颖 刘建强 于 2019-10-30 设计创作，主要内容包括：本发明提供一种Y型分子筛及其制备方法。所述分子筛的晶胞常数为2.415-2.440nm；所述分子筛的～(27)Al MAS NMR谱中化学位移为0±2ppm共振信号的峰面积占总峰面积的比例不大于4％；所述分子筛的强酸量占总酸量的比例为70％以上。本发明的Y分子筛硅铝比高,晶胞常数小,晶体结构完整,微孔比表面积大,二次孔较为丰富,非骨架铝少,具有更高的强酸中心比例,在加氢裂化等烃类裂化反应中具有更高的反应活性,二次反应少,反应选择性好,同时酸性稳定性好,失活缓慢。(The invention provides a Y-type molecular sieve and a preparation method thereof. The unit cell constant of the molecular sieve is 2.415-2.440 nm; of said molecular sieves 27 The proportion of the peak area of the resonance signal with the chemical shift of 0 +/-2 ppm in the Al MAS NMR spectrum to the total peak area is not more than 4 percent; the strong acid amount of the molecular sieve accounts for more than 70 percent of the total acid amount. The Y molecular sieve has the advantages of high silicon-aluminum ratio, small unit cell constant, complete crystal structure, large specific surface area of micropores, rich secondary pores, less non-framework aluminum, higher strong acid center proportion, higher reaction activity in hydrocarbon cracking reactions such as hydrocracking and the like, less secondary reaction, good reaction selectivity, good acid stability and slow inactivation.)

1. A Y-type molecular sieve, characterized in that the molecular sieve has a unit cell constant of 2.415 to 2.440 nm; of said molecular sieves²⁷The proportion of the peak area of the resonance signal with the chemical shift of 0 +/-2 ppm in the Al MAS NMR spectrum to the total peak area is not more than 4 percent; the strong acid amount of the molecular sieve accounts for more than 70 percent of the total acid amount.

2. The Y-type molecular sieve of claim 1,the unit cell constant of the molecular sieve is 2.422-2.438 nm; of said molecular sieves²⁷The proportion of the peak area of the resonance signal with the chemical shift of 0 +/-2 ppm in the Al MAS NMR spectrum to the total peak area is not more than 3 percent; the strong acid amount of the molecular sieve accounts for more than 75 percent of the total acid amount.

3. The Y-type molecular sieve of claim 1, wherein the molecular sieve has a specific surface area of micropores of 650m²More than g; the proportion of the mesopore volume of the molecular sieve in the total pore volume is 30-50%.

4. The Y-type molecular sieve of claim 3, wherein the molecular sieve has a specific surface area of micropores of 700m²More than g; the proportion of the mesoporous volume of the molecular sieve in the total pore volume is 33-45%.

5. A process for the preparation of a Y-type molecular sieve according to any one of claims 1 to 4, characterized in that it comprises:

mixing the NaY molecular sieve with ammonium salt and water to carry out primary ammonium exchange treatment to obtain a primary ammonium exchange molecular sieve;

carrying out first hydrothermal roasting treatment on the first ammonium exchange molecular sieve in a steam atmosphere to obtain a first water-roasted molecular sieve;

mixing the first water-baked molecular sieve with water, and adding a first dealuminizing agent to carry out first dealuminization treatment to obtain a first dealuminized molecular sieve;

carrying out second hydrothermal roasting treatment on the first dealuminized molecular sieve in a steam atmosphere to obtain a second hydrothermal roasted molecular sieve;

mixing the second water-baked molecular sieve with water, and adding a second dealuminizing agent for second dealuminization treatment to obtain a second dealuminized molecular sieve;

carrying out third hydrothermal roasting treatment on the second dealuminized molecular sieve in a steam atmosphere to obtain a third water-roasted molecular sieve;

mixing the third-time water-baked molecular sieve with water, and adding a third dealuminizing agent to carry out third dealuminizing treatment to obtain a third dealuminized molecular sieve; and

mixing the third dealuminized molecular sieve with water, adding a fourth dealuminizing agent for fourth dealuminization treatment, filtering and washing to obtain the Y-type molecular sieve,

wherein the fourth dealuminating agent comprises a silicon-containing dealuminating agent.

6. A method of producing as claimed in claim 5 wherein the first, second and third dealuminating agents are each independently selected from one or more of organic acids selected from ethylenediaminetetraacetic acid, oxalic acid, citric acid and sulfosalicylic acid, inorganic acids selected from fluorosilicic acid, hydrochloric acid, sulfuric acid and nitric acid and organic and inorganic salts selected from ammonium oxalate, ammonium fluoride, ammonium fluorosilicate and ammonium fluoroborate.

7. A method of producing as claimed in claim 5 wherein the silicon-containing dealuminating agent is fluorosilicic acid, ammonium fluorosilicate or a mixture of fluorosilicic acid and ammonium fluorosilicate.

8. The preparation method according to claim 5, wherein the fourth dealuminating agent further comprises an organic acid and/or an inorganic acid, and the mass ratio of the silicon-containing dealuminating agent to the organic acid and/or the inorganic acid is 0.02-0.3: 0-0.07, the organic acid is selected from one or more of ethylenediamine tetraacetic acid, oxalic acid, citric acid and sulfosalicylic acid, and the inorganic acid is selected from one or more of hydrochloric acid, sulfuric acid and nitric acid.

9. The production method according to claim 5, wherein the first hydrothermal calcination, the second hydrothermal calcination, and the third hydrothermal calcination are carried out at a temperature of 350 to 700 ℃, a water vapor concentration of 1 to 100%, and a calcination time of 0.5 to 10 hours.

10. The method according to claim 5, wherein the temperature of the first ammonium exchange treatment is room temperature to 95 ℃, and the treatment time is 0.5 hours to 5 hours; the temperature of the first dealuminization treatment is between room temperature and 90 ℃, and the treatment time is between 0.5 and 6 hours; the temperature of the second dealuminization treatment is between room temperature and 100 ℃, and the treatment time is between 0.5 and 6 hours; the temperature of the third dealuminization treatment is between room temperature and 100 ℃, and the treatment time is 0.5 to 6 hours; the temperature of the fourth dealuminization treatment is between room temperature and 100 ℃, and the treatment time is between 0.5 and 6 hours.

11. The production method according to any one of claims 5 to 10, characterized in that an ammonium salt is added to at least one of the first dealumination treatment, the second dealumination treatment, the third dealumination treatment and the fourth dealumination treatment.

12. The method according to claim 11, wherein the ammonium salt is one or more selected from the group consisting of ammonium chloride, ammonium nitrate, ammonium carbonate, ammonium bicarbonate, ammonium oxalate, ammonium sulfate, and ammonium bisulfate.

13. The method according to claim 12, wherein in the first ammonium exchange treatment, the NaY molecular sieve: the ammonium salt: water 1: 0.3-1.0: 5 to 10.

14. The method of claim 12, wherein in the first dealumination treatment, the first water-calcined molecular sieve has a mass ratio of: the ammonium salt: the first dealuminizing agent: water 1: 0-0.50: 0.02-0.3: 5 to 10.

15. The production method according to claim 12, wherein in the second dealumination treatment, the second-stage water-calcined molecular sieve is: the ammonium salt: the second dealuminizing agent: water 1: 0-0.50: 0.02-0.3: 5 to 10.

16. The method of claim 12, wherein in the third dealumination treatment, the third water-calcined molecular sieve: the ammonium salt: the third dealuminizing agent: water 1: 0-0.70: 0.02-0.3: 5 to 10.

17. The method of claim 12, wherein in the fourth dealumination treatment, the third dealumination molecular sieve is: the ammonium salt: the silicon-containing dealuminizing agent comprises the following components: water 1: 0-0.70: 0.02-0.3: 5 to 10.

Technical Field

The invention relates to the field of catalysis, in particular to a modified Y-type molecular sieve and a preparation method thereof.

Background

The quality of catalytic cracking diesel oil is increasingly deteriorated due to various factors such as the application of catalytic cracking technologies for improving the quality of crude oil, the deterioration degree of crude oil, the quality of gasoline, the yield of propylene and the like, and the factors are represented as high density, high nitrogen content, high aromatic hydrocarbon content and low cetane number. Aiming at the composition characteristic that secondary processing diesel oil, especially catalytic diesel oil is rich in polycyclic aromatic hydrocarbon, a hydrocracking process is adopted to make polycyclic aromatic hydrocarbon in the secondary processing diesel oil undergo hydrogenation saturation and ring-opening cracking to produce high-octane gasoline or light aromatic hydrocarbon, so that inferior diesel oil can be better and more fully utilized, and remarkable economic benefit is brought to enterprises. Hydrocracking catalysts are, of course, the heart of this technology.

The hydrogenation catalyst is a bifunctional catalyst with hydrogenation and cracking functions, and consists of an acidic cracking component and a metal hydrogenation component, wherein the Y-shaped molecular sieve plays an important role in the hydrogenation catalyst as a main acidic cracking component and a carrier, and the silicon-aluminum ratio, the acid property, the pore structure and other physicochemical properties of the molecular sieve influence the reaction performance of the hydrogenation catalyst; the stronger acid centers on the molecular sieve are beneficial to improving the cracking activity, the moderate acid center quantity and acid density are beneficial to reducing secondary reaction and improving the reaction selectivity while the cracking activity is not reduced, and the proper pore diameter and the unobstructed pore channel are beneficial to the diffusion of reactants and product molecular sieves, reduce coking, improve the reaction selectivity and prolong the service life of the catalyst.

The synthesized NaY molecular sieve has low silica-alumina ratio and no acidity, and needs to be modified. The modification means for improving the silicon-aluminum ratio of the molecular sieve mainly comprises two methods, namely hydrothermal roasting and chemical dealumination, wherein the hydrothermal roasting enables the molecular sieve to generate framework dealumination and silicon supplementation, so that the silicon-aluminum ratio of a framework of the molecular sieve is improved, but aluminum removed from the framework exists in pore channels of the molecular sieve in a non-framework aluminum form, so that pore channel blockage and acidity change are caused. Chemical dealumination employs various acids or complexing agents to interact with aluminum in the molecular sieve to remove aluminum from the molecular sieve. Thus hydrothermal roasting and chemical dealumination are often combined for better results.

CN1253860A discloses a middle distillate oil type hydrocracking catalyst containing Y zeolite and a preparation method thereof, wherein a hydrophobic Y molecular sieve used in the preparation method adopts multiple ammonium exchanges or one-time water roasting and multiple ammonium exchanges to obtain a Y molecular sieve with the sodium oxide content of less than 0.2 w%, and the Y molecular sieve is obtained after water roasting and dealumination, the molecular sieve has the characteristics of high silicon-aluminum ratio and low acid content, and contains moderate secondary pores, but the requirement on the sodium oxide content in the preparation process is rigorous, and the non-framework aluminum content of a molecular sieve product is high, so that the acid strength of the molecular sieve is weakened, the smoothness degree of the secondary pores of the molecular sieve is influenced, the diffusion of reactant molecules and product molecules is hindered, and the reaction selectivity is influenced finally.

CN1951814A discloses a modified Y zeolite and a preparation method thereof, the zeolite is prepared by hydrothermal treatment and chemical dealumination, has more secondary pores and higher crystallinity, but the final step is hydrothermal roasting, which causes the non-framework aluminum content of a molecular sieve product to be high, and influences the reaction activity and selectivity.

CN104250010A discloses a silicon-aluminum carrier containing two modified molecular sieves and a preparation method thereof, wherein a Y molecular sieve is prepared by twice water roasting, repeated exchange and dealumination. The obtained molecular sieve has high silicon-aluminum ratio, low acid center density and high secondary pore ratio. However, the multiple dealumination before the second baking of the molecular sieve easily causes crystal defects, so that the crystal structure is more easily collapsed in the water baking process, a large amount of non-framework aluminum is generated, and the non-framework aluminum is not easily cleaned in the subsequent dealumination.

CN106629764A discloses a dealuminized Y molecular sieve and a preparation method thereof, the non-framework aluminum content of the molecular sieve is relatively low, but the proportion of secondary pores in total pores is slightly smaller, and the total silicon-aluminum ratio is lower.

Although various Y molecular sieves and preparation methods thereof have been disclosed, they all have shortcomings in physicochemical properties such as silica-alumina ratio, acid properties, and pore structure, and thus it is difficult to satisfy the requirements for catalyst performance.

It is noted that the information disclosed in the foregoing background section is only for enhancement of background understanding of the invention and therefore it may contain information that does not constitute prior art that is already known to a person of ordinary skill in the art.

Disclosure of Invention

The invention aims to provide a Y-type molecular sieve with high silicon-aluminum ratio, less non-framework aluminum and high strong acid ratio aiming at the defects of the prior art.

In order to achieve the purpose, the invention adopts the following technical scheme:

a Y-type molecular sieve having a unit cell constant of from 2.415 to 2.440 nm; of said molecular sieves²⁷The proportion of the peak area of the resonance signal with the chemical shift of 0 +/-2 ppm in the Al MAS NMR spectrum to the total peak area is not more than 4 percent; the strong acid amount of the molecular sieve accounts for more than 70 percent of the total acid amount.

In some embodiments, the molecular sieve has a unit cell constant of 2.422-2.438 nm; of said molecular sieves²⁷The proportion of the peak area of the resonance signal with the chemical shift of 0 +/-2 ppm in the Al MAS NMR spectrum to the total peak area is not more than 3 percent; the strong acid amount of the molecular sieve accounts for more than 75 percent of the total acid amount.

In some embodiments, the molecular sieve has a micropore specific surface area of 650m²More than g; the proportion of the mesopore volume of the molecular sieve in the total pore volume is 30-50%.

In some embodiments, the molecular sieve has a specific surface area of micropores of 700m²More than g; the proportion of the mesoporous volume of the molecular sieve in the total pore volume is 33-45%.

On the other hand, the invention also provides a preparation method of the Y-type molecular sieve, which comprises the following steps:

mixing the NaY molecular sieve with ammonium salt and water to carry out primary ammonium exchange treatment to obtain a primary ammonium exchange molecular sieve;

carrying out first hydrothermal roasting treatment on the first-time ammonium exchange molecular sieve in a steam atmosphere to obtain a first-time water roasted molecular sieve;

mixing the first water-baked molecular sieve with water, and adding a first dealuminizing agent to carry out first dealuminization treatment to obtain a first dealuminized molecular sieve;

carrying out second hydrothermal roasting treatment on the second ammonium exchange molecular sieve in a steam atmosphere to obtain a second hydrothermal roasted molecular sieve;

mixing the second water-baked molecular sieve with water, and adding a second dealuminizing agent for second dealuminization treatment to obtain a second dealuminized molecular sieve;

carrying out third hydrothermal roasting treatment on the second dealuminized molecular sieve in a steam atmosphere to obtain a third water-roasted molecular sieve;

mixing the third-time water-baked molecular sieve with water, and adding a third dealuminizing agent to carry out third dealuminizing treatment to obtain a third dealuminized molecular sieve; and

mixing the third dealuminized molecular sieve with water, adding a fourth dealuminizing agent for fourth dealuminization treatment, filtering and washing to obtain the Y-type molecular sieve,

wherein the fourth dealuminating agent comprises a silicon-containing dealuminating agent.

In some embodiments, the first, second, and third dealuminating agents are each independently selected from one or more of organic acids selected from ethylenediaminetetraacetic acid, oxalic acid, citric acid, and sulfosalicylic acid, inorganic acids selected from fluorosilicic acid, hydrochloric acid, sulfuric acid, and nitric acid, and organic and inorganic salts selected from ammonium oxalate, ammonium fluoride, ammonium fluorosilicate, and ammonium fluoroborate.

In some embodiments, the silicon-containing dealuminating agent is fluorosilicic acid, ammonium fluorosilicate, or a mixture of fluorosilicic acid and ammonium fluorosilicate.

In some embodiments, the fourth dealuminating agent further comprises an organic acid and/or an inorganic acid, and the mass ratio of the silicon-containing dealuminating agent to the organic acid and/or the inorganic acid is 0.02-0.3: 0-0.07, the organic acid is selected from one or more of ethylenediamine tetraacetic acid, oxalic acid, citric acid and sulfosalicylic acid, and the inorganic acid is selected from one or more of hydrochloric acid, sulfuric acid and nitric acid.

In some embodiments, the first hydrothermal roasting treatment, the second hydrothermal roasting treatment and the third hydrothermal roasting treatment are performed at a temperature of 350 to 700 ℃, a water vapor concentration of 1 to 100%, and a roasting time of 0.5 to 10 hours.

In some embodiments, the temperature of the first ammonium exchange treatment is between room temperature and 95 ℃, and the treatment time is between 0.5 and 5 hours; the temperature of the first dealuminization treatment is between room temperature and 90 ℃, and the treatment time is between 0.5 and 6 hours; the temperature of the second dealuminization treatment is between room temperature and 100 ℃, and the treatment time is between 0.5 and 6 hours; the temperature of the third dealuminization treatment is between room temperature and 100 ℃, and the treatment time is 0.5 to 6 hours; the temperature of the fourth dealuminization treatment is between room temperature and 100 ℃, and the treatment time is between 0.5 and 6 hours.

In some embodiments, an ammonium salt is added to at least one of the first dealumination treatment, the second dealumination treatment, the third dealumination treatment and the fourth dealumination treatment.

In some embodiments, the ammonium salt is selected from one or more of ammonium chloride, ammonium nitrate, ammonium carbonate, ammonium bicarbonate, ammonium oxalate, ammonium sulfate, ammonium bisulfate.

In some embodiments, in the first ammonium exchange treatment, the NaY molecular sieve: the ammonium salt: water 1: 0.3-1.0: 5 to 10.

In some embodiments, in the first dealumination treatment, the first water-calcined molecular sieve: the ammonium salt: the first dealuminizing agent: water 1: 0-0.50: 0.02-0.3: 5 to 10.

In some embodiments, in the second dealumination treatment, the second water-calcined molecular sieve: the ammonium salt: the second dealuminizing agent: water 1: 0-0.50: 0.02-0.3: 5 to 10.

In some embodiments, in the third dealumination treatment, the third water-calcined molecular sieve: the ammonium salt: the third dealuminizing agent: water 1: 0-0.70: 0.02-0.3: 5 to 10.

In some embodiments, in the fourth dealumination treatment, the third dealumination molecular sieve is: the ammonium salt: the silicon-containing dealuminizing agent comprises the following components: water 1: 0-0.70: 0.02-0.3: 5 to 10.

The Y molecular sieve has the advantages of high silicon-aluminum ratio, small unit cell constant, complete crystal structure, large specific surface area of micropores, rich secondary pores, less non-framework aluminum, higher strong acid center proportion, higher reaction activity in hydrocarbon cracking reactions such as hydrocracking and the like, less secondary reaction, good reaction selectivity, good acid stability and slow inactivation.

Detailed Description

The technical solution of the present invention is further explained below according to specific embodiments. The scope of protection of the invention is not limited to the following examples, which are set forth for illustrative purposes only and are not intended to limit the invention in any way.

In the present invention, anything or matters not mentioned is directly applicable to those known in the art without any change except those explicitly described. Moreover, any embodiment described herein may be freely combined with one or more other embodiments described herein, and the technical solutions or ideas thus formed are considered part of the original disclosure or original description of the present invention, and should not be considered as new matters not disclosed or contemplated herein, unless a person skilled in the art would consider such combination to be clearly unreasonable.

All features disclosed in this invention may be combined in any combination and such combinations are understood to be disclosed or described herein unless a person skilled in the art would consider such combinations to be clearly unreasonable. The endpoints of the ranges and any values disclosed herein are not limited to the precise range or value, and such ranges or values should be understood to encompass values close to those ranges or values. For ranges of values, between the endpoints of each of the ranges and the individual points, and between the individual points may be combined with each other to give one or more new ranges of values, and these ranges of values should be considered as specifically disclosed herein.

According to a first aspect of the present invention there is provided a modified Y-type molecular sieve having a unit cell constant in the range 2.415 to 2.440nm, preferably a unit cell constant in the range 2.422 to 2.438 nm; specific surface area of micropores is 650m²A ratio of 700m or more, preferably 700m²More than g; the mesopore volume accounts for 30 to 50 percent of the total pore volume, preferably 33 to 45 percent; of molecular sieves²⁷Al MAS NMThe proportion of the peak area of resonance signals with the chemical shift of 0 +/-2 ppm in the R spectrum to the total peak area is not more than 4 percent, and preferably not more than 3 percent; the proportion of the strong acid amount of the molecular sieve to the total acid amount is 70% or more, preferably 75% or more.

The strong acid of the Y-type molecular sieve in the invention is NH₃Temperature programmed desorption (NH)₃Acid with desorption temperature higher than 320 ℃ in the TPD) curve, the ratio of the amount of strong acid to the total amount of acid is NH₃The desorption temperature in the TPD results is greater than the ratio of the amount of strong acid at 320 ℃ to the total acid.

From the physicochemical parameters, the Y-type molecular sieve has the advantages of high silicon-aluminum ratio, small unit cell constant, complete crystal structure, large specific surface area of micropores, rich secondary pores, less non-framework aluminum, high proportion of strong acid centers and the like.

The Y-type molecular sieve is prepared by taking an NaY molecular sieve as a raw material and performing multiple exchange, dealumination and three times of hydrothermal roasting, wherein dealumination treatment is performed at least once before the second time and the third time of hydrothermal roasting, dealumination is performed at least twice continuously after the third time of hydrothermal roasting, and a silicon-containing dealumination agent is used in the last dealumination process.

Specifically, the preparation method of the Y-type molecular sieve of the invention can comprise the following steps:

mixing the NaY molecular sieve with ammonium salt and water to carry out primary ammonium exchange treatment to obtain a primary ammonium exchange molecular sieve;

carrying out first hydrothermal roasting treatment on the first-time ammonium exchange molecular sieve in a steam atmosphere to obtain a first-time water-roasted molecular sieve;

mixing the first water-baked molecular sieve with water, and adding a first dealuminizing agent to carry out first dealuminization treatment to obtain a first dealuminized molecular sieve;

carrying out second hydrothermal roasting treatment on the first dealuminized molecular sieve in a steam atmosphere to obtain a second hydrothermal roasted molecular sieve;

mixing the second water-baked molecular sieve with water, and adding a second dealuminizing agent for second dealuminization treatment to obtain a second dealuminized molecular sieve;

carrying out third hydrothermal roasting treatment on the second dealuminized molecular sieve in a steam atmosphere to obtain a third hydrothermal roasted molecular sieve;

mixing the third-time water-baked molecular sieve with water, and adding a third dealuminizing agent to carry out third dealuminizing treatment to obtain a third dealuminized molecular sieve; and

mixing the third dealuminized molecular sieve with water, adding a fourth dealuminizing agent for fourth dealuminization treatment, filtering and washing to obtain a Y-type molecular sieve,

wherein the fourth dealuminizing agent comprises a silicon-containing dealuminizing agent.

In the production method of the present invention, the ammonium salts used in the ammonium exchange treatment are each independently one or more selected from the group consisting of ammonium chloride, ammonium nitrate, ammonium carbonate, ammonium hydrogencarbonate, ammonium oxalate, ammonium sulfate and ammonium bisulfate.

In the preparation method of the invention, the first ammonium exchange treatment is to mix NaY zeolite (namely NaY molecular sieve) with ammonium salt and water according to the weight ratio of NaY molecular sieve: ammonium salt: water 1: 0.3-1.0: 5-10 to obtain slurry, treating the slurry at room temperature to 95 ℃ for 0.5-5 hours, washing and drying the slurry to obtain the first ammonium exchange molecular sieve. Wherein, the NaY molecular sieve is based on the weight of a dry basis (the weight of the molecular sieve after being calcined for 1 hour at 800 ℃ in the invention).

In the preparation method, the first hydrothermal roasting treatment is to roast the first ammonium exchange molecular sieve for 0.5 to 10 hours at the temperature of 350 to 700 ℃ in the atmosphere of 1 to 100 percent of water vapor to obtain the first hydrothermal roasting molecular sieve.

In the preparation method of the invention, the first dealumination treatment is carried out according to the following steps of first water roasting molecular sieve: optional ammonium salts: a first dealuminizing agent: water 1: 0-0.50: 0.02-0.3: 5-10, mixing water with the first-time water-baked molecular sieve and optional ammonium salt, adding a first dealumination agent, treating at room temperature to 90 ℃ for 0.5-6 hours, filtering, and washing to obtain a first-time dealumination molecular sieve, wherein the first-time water-baked molecular sieve is based on dry weight.

In the preparation method, the second hydrothermal roasting treatment is to roast the first dealuminized molecular sieve for 0.5 to 10 hours at the temperature of 350 to 700 ℃ in the atmosphere of 1 to 100 percent of water vapor to obtain the second hydrothermal roasted molecular sieve.

In the preparation method of the invention, the second dealumination treatment is carried out according to the following steps of water roasting molecular sieve for the second time: optional ammonium salts: a second dealuminizing agent: water 1: 0-0.50: 0.02-0.3: 5-10, mixing water with the second-time water-baked molecular sieve and optional ammonium salt, adding a second dealuminizing agent, treating at room temperature to 100 ℃ for 0.5-6 hours, filtering, and washing to obtain a second-time dealuminized molecular sieve, wherein the second-time water-baked molecular sieve is based on dry weight.

In the preparation method, the third hydrothermal roasting treatment is to roast the second dealuminized molecular sieve for 0.5 to 10 hours at the temperature of 350 to 700 ℃ in the atmosphere of 1 to 100 percent of water vapor to obtain the third hydrothermal roasted molecular sieve.

In the preparation method of the invention, the third dealuminization treatment is carried out according to the following steps of water roasting molecular sieve: optional ammonium salts: a third dealuminizing agent: water 1: 0-0.70: 0.02-0.3: 5-10, mixing water with the third-time water-baked molecular sieve and optional ammonium salt, adding a third dealuminizing agent, treating at room temperature to 100 ℃ for 0.5-6 hours, filtering, and washing to obtain a third-time dealuminized molecular sieve, wherein the third-time water-baked molecular sieve is based on dry weight.

In the preparation method of the invention, the fourth dealumination treatment is carried out according to the third dealumination molecular sieve: optional ammonium salts: silicon-containing dealuminizing agent: organic and/or inorganic acids: water 1: 0-0.70: 0.02-0.3: 0-0.07: 5-10, mixing the third dealuminized molecular sieve with optional ammonium salt and water, adding a fourth dealuminizing agent (at least comprising a silicon-containing dealuminizing agent, and further comprising organic acid and/or inorganic acid), treating at room temperature-100 ℃ for 0.5-6 hours, filtering and washing to obtain the fourth dealuminized molecular sieve, wherein the third dealuminized molecular sieve is based on dry weight.

In the preparation method of the present invention, the first dealuminating agent, the second dealuminating agent and the third dealuminating agent may be the same or different and are each independently selected from one or more of organic acids, inorganic acids and organic and inorganic salts, wherein the organic acids are selected from ethylenediaminetetraacetic acid, oxalic acid, citric acid and sulfosalicylic acid, the inorganic acids are selected from fluorosilicic acid, hydrochloric acid, sulfuric acid and nitric acid, and the organic and inorganic salts are selected from ammonium oxalate, ammonium fluoride, ammonium fluorosilicate and ammonium fluoroborate.

In the preparation method of the invention, the dealumination agent used in the last dealumination treatment (i.e. the fourth dealumination treatment) comprises a silicon-containing dealumination agent, and can further comprise organic acid and/or inorganic acid, wherein the silicon-containing dealumination agent is fluosilicic acid, ammonium fluosilicate or a mixture of fluosilicic acid and ammonium fluosilicate, the organic acid in the organic acid and/or the inorganic acid is selected from one or more of ethylenediamine tetraacetic acid, oxalic acid, citric acid and sulfosalicylic acid, and the inorganic acid is selected from one or more of hydrochloric acid, sulfuric acid and nitric acid.

The Y-type molecular sieve is prepared by multiple dealumination and three times of water roasting, aluminum vacancies formed in the dealumination process can be filled with silicon as much as possible in the water roasting process, the generated non-framework aluminum is gradually stripped through multiple dealumination, and the three times of hydrothermal roasting and the multiple dealumination supplement each other, so that the completeness of crystals is kept, and more strong acid centers are reserved.

Therefore, the Y-type molecular sieve has the advantages of high silicon-aluminum ratio, less non-framework aluminum, high strong acid center ratio, large specific surface area, rich secondary pores, higher reaction activity in hydrocarbon cracking reactions such as hydrocracking and the like, less secondary reaction, good ring-opening reaction selectivity, good acid stability and slow inactivation.

The present invention will be described in detail with reference to examples, but the scope of the present invention is not limited thereto.

Examples

In the examples and comparative examples, the specifications of the raw materials used were as follows:

NaY molecular sieve, industrial product, silicon-aluminium ratio is greater than 4.7, crystallinity is greater than 85%

Sulfuric acid, chemical purity

Hydrochloric acid, chemical purity

Nitric acid, chemical purity

Oxalic acid, solid, chemically pure

Fluosilicic acid, technical grade

Ammonium nitrate, chemical purity

Ammonium chloride, chemical purity

Ammonium oxalate, chemical purity

Ammonium sulfate, chemical purity

In the examples and comparative examples, the apparatus and test methods involved are as follows:

the cell constants were measured by X-ray diffraction (XRD) using RIPP145-90 standard method (see "analytical methods in petrochemical industry (RIPP test method)", Yangshui et al, scientific Press, 1990 edition).

Measuring the micropore specific surface area of the molecular sieve by adopting a nitrogen adsorption BET specific surface area method; the mesoporous refers to a molecular sieve pore canal with the pore diameter larger than 2 nanometers and smaller than 50 nanometers, and the pore volume is determined by adopting a GB/T5816-.

²⁷The Al MAS NMR is tested by a Bruker Avance III 500MHz nuclear magnetic resonance instrument, and each peak area is calculated by an integration method after a resonance peak spectrogram is subjected to peak-splitting fitting.

The acid amount is NH₃TPD method, see methods for solid catalyst research, petrochemicals, 30(12), 2001: 952 "in which the amount of strong acid refers to NH₃The peak temperature of desorption peak is larger than the acid center number above 320 ℃.

The chemical silica-alumina ratio was measured by X-ray fluorescence. Namely, the content of the silicon oxide and the aluminum oxide is calculated, and the content of the silicon oxide and the aluminum oxide is measured by adopting the GB/T30905-2014 standard method.

Example 1

(1) Exchanging NaY zeolite serving as a raw material by using an ammonium sulfate solution, wherein the treatment conditions are as follows: according to NaY molecular sieve (dry basis): ammonium sulfate: water 1: 1.0: 10, exchange at 90 ℃ for 2h, filter, wash with deionized water, and dry at 120 ℃ for 4 h.

(2) And (2) carrying out first hydrothermal roasting treatment on the molecular sieve obtained in the step (1), wherein the roasting temperature is 520 ℃, and roasting for 2h in a 100% steam atmosphere.

(3) And (3) mixing the molecular sieve obtained in the step (2) according to the mass ratio of the molecular sieve (dry basis): sulfuric acid: ammonium chloride: water 1: 0.06: 0.40: 9, pulping the molecular sieve by adding water, slowly dripping 20 percent sulfuric acid, controlling the dripping time for 30min, heating, treating at 70 ℃ for 40min, filtering, washing by deionized water, and drying at 120 ℃ for 4 h.

(4) And (4) carrying out second hydrothermal roasting treatment on the molecular sieve obtained in the step (3), wherein the roasting temperature is 620 ℃, and roasting for 2 hours in a 100% steam atmosphere.

(5) And (3) mixing the molecular sieve obtained in the step (4) according to the mass ratio of the molecular sieve (dry basis): sulfuric acid: water 1: 0.09: and 8, adding water into the molecular sieve, pulping, slowly dropwise adding 20% sulfuric acid, controlling the dropwise adding time for 30min, heating to 70 ℃, treating for 60min, filtering, washing with deionized water, and drying at 120 ℃ for 4 h.

(6) And (5) carrying out a third hydrothermal roasting treatment on the molecular sieve obtained in the step (5), wherein the roasting temperature is 650 ℃, and roasting for 2 hours in a 100% water vapor atmosphere.

(7) And (3) mixing the molecular sieve obtained in the step (7) according to the mass ratio of the molecular sieve (dry basis): sulfuric acid: water 1: 0.09: and 8, adding water into the molecular sieve, pulping, slowly dropwise adding 30% sulfuric acid, controlling the dropwise adding time for 40min, heating, treating at 70 ℃ for 60min, filtering, and washing with deionized water.

(8) And (3) mixing the molecular sieve obtained in the step (7) according to the following molecular sieve: ammonium sulfate: fluosilicic acid, sulfuric acid: h₂Adding water into the molecular sieve for pulping, adding ammonium sulfate, slowly dropwise adding 30% fluosilicic acid and 20% sulfuric acid, controlling the dropwise adding time for 40min, heating, treating at 80 ℃ for 90min, filtering, and washing with deionized water to obtain the molecular sieve Y-1, wherein all parameters are shown in Table 1.

Example 2

(1) Exchanging NaY zeolite serving as a raw material by using an ammonium sulfate solution, wherein the treatment conditions are as follows: according to NaY molecular sieve (dry basis): ammonium sulfate: water 1:0.5: 7, exchange at 80 ℃ for 1h, filter, wash with deionized water, and dry at 120 ℃ for 4 h.

(2) And (2) carrying out first hydrothermal roasting treatment on the molecular sieve obtained in the step (1), wherein the roasting temperature is 670 ℃, and roasting for 2h in a 100% steam atmosphere.

(3) And (3) mixing the molecular sieve obtained in the step (2) according to the mass ratio of the molecular sieve (dry basis): oxalic acid: ammonium nitrate: water 1: 0.20: 0.40: 9, firstly adding water into the molecular sieve for pulping, adding ammonium nitrate and oxalic acid under stirring at room temperature, stirring for 60min, filtering, washing twice by deionized water, and drying at 120 ℃ for 3 h.

(4) And (4) carrying out second hydrothermal roasting treatment on the molecular sieve obtained in the step (3), wherein the roasting temperature is 645 ℃, and roasting for 2.5 hours in a 100% steam atmosphere.

(5) Adding 7 times of water into the molecular sieve obtained in the step (4), pulping, heating the pulp to 60 ℃, and then adding the following components in percentage by weight: nitric acid: ammonium oxalate: water 1: 0.13: 0.2, preparing ammonium oxalate, nitric acid and water into a solution, adding the aqueous solution into the molecular sieve slurry, controlling the dropping time to be 30min, continuously stirring at 60 ℃ for 40min, filtering, washing by deionized water, and drying at 105 ℃ for 2 h.

(6) And (5) carrying out a third hydrothermal roasting treatment on the molecular sieve obtained in the step (5), wherein the roasting temperature is 670 ℃, and roasting for 2h in a 100% water vapor atmosphere.

(7) And (3) mixing the molecular sieve obtained in the step (6) according to the mass ratio of the molecular sieve (dry basis): sulfuric acid: ammonium nitrate: water 1: 0.13: 0.30: 9, firstly adding a proper amount of water into the molecular sieve, pulping, then adding ammonium nitrate, then adding 30% sulfuric acid aqueous solution at a constant speed, controlling the dropping time for 40min, heating, treating at 70 ℃ for 60min, filtering, washing by deionized water, and drying at 120 ℃ for 4 h.

(8) And (3) mixing the molecular sieve obtained in the step (7) according to the following molecular sieve: ammonium sulfate: h₂SiF₆：H₂O is 1:0.2: 0.15: 7, adding water into the molecular sieve, pulping, adding ammonium sulfate, slowly adding 30% fluosilicic acid dropwise, controlling the dropwise adding time for 60min, heating, treating at 60 ℃ for 50min, filtering, washing with deionized water, and drying at 120 ℃ to obtain the molecular sieve Y-2, wherein all parameters are shown in table 1.

Example 3

(1) Exchanging NaY zeolite serving as a raw material with an ammonium chloride solution, wherein the treatment conditions are as follows: according to NaY molecular sieve (dry basis): ammonium chloride: water 1: 0.7: 10, exchange at 85 ℃ for 1h, filter, wash with deionized water, and dry at 120 ℃ for 4 h.

(2) And (2) carrying out first hydrothermal roasting treatment on the molecular sieve obtained in the step (1), wherein the roasting temperature is 600 ℃, and roasting for 2h in a 100% steam atmosphere.

(3) And (3) mixing the molecular sieve obtained in the step (2) according to the mass ratio of the molecular sieve (dry basis): citric acid: sulfuric acid: water 1: 0.15: 0.05: and 8, adding water into the molecular sieve, pulping, heating, adding 20% sulfuric acid at a constant speed at 70 ℃ under stirring, controlling the dropping time for 30min, adding 20% citric acid aqueous solution, controlling the dropping time for 20min, continuously stirring at 70 ℃ for 1h after the addition is finished, filtering, washing with deionized water, and drying at 120 ℃ for 4 h.

(4) And (4) carrying out second hydrothermal roasting treatment on the molecular sieve obtained in the step (3), wherein the roasting temperature is 600 ℃, and roasting for 2 hours in a 100% steam atmosphere.

(5) And (3) mixing the molecular sieve obtained in the step (4) according to the mass ratio of the molecular sieve (dry basis): hydrochloric acid: ammonium sulfate: water 1: 0.06: 0.1: 10, adding water into the molecular sieve, pulping, adding ammonium sulfate, stirring uniformly, slowly dropwise adding hydrochloric acid with the concentration of 15%, controlling the dropwise adding time to be 1h, heating to 60 ℃, treating for 40min, filtering, washing with deionized water, and drying at 120 ℃ for 4 h.

(6) And (4) carrying out third hydrothermal roasting treatment on the molecular sieve obtained in the step (5), wherein the roasting temperature is 550 ℃, and roasting for 3 hours in a 100% water vapor atmosphere.

(7) And (3) mixing the molecular sieve obtained in the step (6) according to the mass ratio of the molecular sieve (dry basis): hydrochloric acid: oxalic acid: ammonium sulfate: water 1: 0.05: 0.19: 0.1: 10, adding water into the molecular sieve, pulping, adding ammonium sulfate, slowly dripping hydrochloric acid with the concentration of 10%, controlling the dripping time for 40min, adding oxalic acid, heating, treating at 70 ℃ for 60min, filtering, and washing with deionized water.

(8) Sieving the molecular sieve obtained in the step (7) according to a molecular sieve; ammonium chloride: fluosilicic acid, hydrochloric acid: h₂Adding water into a molecular sieve, pulping, adding ammonium chloride, and slowly adding 30% of solutionControlling the dripping time of fluosilicic acid and hydrochloric acid with the concentration of 20% for 60min, heating, treating at 60 ℃ for 50min, filtering, and washing with deionized water to obtain the molecular sieve Y-3, wherein all parameters are shown in Table 1.

Example 4

(1) Exchanging NaY zeolite serving as a raw material by using an ammonium sulfate solution, wherein the treatment conditions are as follows: according to NaY molecular sieve (dry basis): ammonium sulfate: water 1: 1.0: 10, exchange at 90 ℃ for 2h, filter, wash with deionized water, and dry at 120 ℃ for 4 h.

(2) And (2) carrying out first hydrothermal roasting treatment on the molecular sieve obtained in the step (1), wherein the roasting temperature is 520 ℃, and roasting for 2h in a 100% steam atmosphere.

(3) And (3) mixing the molecular sieve obtained in the step (2) according to the mass ratio of the molecular sieve (dry basis): sulfuric acid: ammonium chloride: water 1: 0.06: 0.40: 9, pulping the molecular sieve by adding water, slowly dripping 20 percent sulfuric acid, controlling the dripping time for 30min, heating, treating at 70 ℃ for 40min, filtering, washing by deionized water, and drying at 120 ℃ for 4 h.

(4) And (4) carrying out second hydrothermal roasting treatment on the molecular sieve obtained in the step (3), wherein the roasting temperature is 620 ℃, and roasting for 2 hours in a 100% steam atmosphere.

(5) And (3) mixing the molecular sieve obtained in the step (4) according to the mass ratio of the molecular sieve (dry basis): sulfuric acid: water 1: 0.09: and 8, adding water into the molecular sieve, pulping, slowly dropwise adding 20% sulfuric acid, controlling the dropwise adding time for 30min, heating to 70 ℃, treating for 60min, filtering, washing with deionized water, and drying at 120 ℃ for 4 h.

(6) And (5) carrying out a third hydrothermal roasting treatment on the molecular sieve obtained in the step (5), wherein the roasting temperature is 650 ℃, and roasting for 2 hours in a 100% water vapor atmosphere.

(7) And (3) mixing the molecular sieve obtained in the step (7) according to the mass ratio of the molecular sieve (dry basis): ammonium sulfate: fluosilicic acid: sulfuric acid: h₂Adding water into a molecular sieve, pulping, adding ammonium sulfate, slowly dropwise adding 30% fluosilicic acid and 20% sulfuric acid, controlling the dropwise adding time for 40min, heating, treating at 80 ℃ for 90min, filtering, and washing with deionized water.

(8) And (3) mixing the molecular sieve obtained in the step (7) according to the following molecular sieve: ammonium sulfate: fluosilicic acid, sulfuric acid: h₂Adding water into the molecular sieve for pulping, adding ammonium sulfate, slowly dropwise adding 30% fluosilicic acid and 20% sulfuric acid, controlling the dropwise adding time for 40min, heating, treating at 80 ℃ for 90min, filtering, and washing with deionized water to obtain the molecular sieve Y-4, wherein all parameters are shown in Table 1.

Comparative example 1

Compared with the preparation process of example 1, step 6 to step 8 were omitted, but step 3 and step 5 were repeated twice, respectively, as follows:

(1) the NaY molecular sieve (silica-alumina molar ratio 5.1) was subjected to ammonium exchange several times until the sodium oxide content was 2.3%.

(2) And (2) carrying out first hydrothermal roasting treatment on the molecular sieve obtained in the step (1), wherein the roasting temperature is 520 ℃, and roasting for 2h in a 100% steam atmosphere.

(3) And (3) mixing the molecular sieve obtained in the step (2) according to the mass ratio of the molecular sieve (dry basis): sulfuric acid: ammonium chloride: water 1: 0.06: 0.40: 9, pulping the molecular sieve by adding water, slowly dripping 20 percent sulfuric acid, controlling the dripping time for 30min, heating, treating at 70 ℃ for 40min, filtering, washing by deionized water, and drying at 120 ℃ for 4 h.

(4) And (4) mixing the molecular sieve obtained in the step (3) according to the mass ratio of the molecular sieve (dry basis): sulfuric acid: ammonium chloride: water 1: 0.06: 0.40: 9, pulping the molecular sieve by adding water, slowly dripping 20 percent sulfuric acid, controlling the dripping time for 30min, heating, treating at 70 ℃ for 40min, filtering, washing by deionized water, and drying at 120 ℃ for 4 h.

(5) And (4) carrying out second hydrothermal roasting treatment on the molecular sieve obtained in the step (4), wherein the roasting temperature is 620 ℃, and roasting for 2 hours in a 100% steam atmosphere.

(6) And (3) mixing the molecular sieve obtained in the step (5) according to the mass ratio of the molecular sieve (dry basis): sulfuric acid: water 1: 0.09: and 8, adding water into the molecular sieve, pulping, slowly dropwise adding 20% sulfuric acid, controlling the dropwise adding time for 30min, heating to 70 ℃, treating for 60min, filtering, washing with deionized water, and drying at 120 ℃ for 4 h.

(7) And (3) mixing the molecular sieve obtained in the step (6) according to the mass ratio of the molecular sieve (dry basis): sulfuric acid: water 1: 0.09: and 8, adding water into the molecular sieve, pulping, slowly dropwise adding 20% sulfuric acid, controlling the dropwise adding time for 30min, heating to 70 ℃, treating for 60min, filtering, washing with deionized water, and drying at 120 ℃ for 4 h. Molecular sieve D-1 of comparative example 1 was obtained, the parameters of which are shown in Table 1.

Comparative example 2

Compared with the preparation process of the example 2, the steps 5 to 7 are omitted, and the specific steps are as follows:

(1) exchanging NaY zeolite serving as a raw material by using an ammonium sulfate solution, wherein the treatment conditions are as follows: according to NaY molecular sieve (dry basis): ammonium sulfate: water 1:0.5: 7, exchange at 80 ℃ for 1h, filter, wash with deionized water, and dry at 120 ℃ for 4 h.

(2) And (2) carrying out first hydrothermal roasting treatment on the molecular sieve obtained in the step (1), wherein the roasting temperature is 670 ℃, and roasting for 2h in a 100% steam atmosphere.

(3) And (3) mixing the molecular sieve obtained in the step (2) according to the mass ratio of the molecular sieve (dry basis): oxalic acid: ammonium nitrate: water 1: 0.20: 0.40: 9, firstly adding water into the molecular sieve for pulping, adding ammonium nitrate and oxalic acid under stirring at room temperature, stirring for 60min, filtering, washing twice by deionized water, and drying at 120 ℃ for 3 h.

(4) And (4) carrying out second hydrothermal roasting treatment on the molecular sieve obtained in the step (3), wherein the roasting temperature is 645 ℃, and roasting for 2.5 hours in a 100% steam atmosphere.

(5) And (3) mixing the molecular sieve obtained in the step (4) according to the following molecular sieve: ammonium sulfate: h₂SiF₆：H₂O is 1:0.2: 0.15: 7, adding water into the molecular sieve, pulping, adding ammonium sulfate, slowly adding 30% fluosilicic acid dropwise, controlling the dropwise adding time for 60min, heating, treating at 60 ℃ for 50min, filtering, washing with deionized water, and drying at 120 ℃ to obtain the molecular sieve D-2, wherein all parameters are shown in table 1.

Comparative example 3

Compared with the preparation process of the example 3, the steps 5 and 6 are omitted, and the specific steps are as follows:

(1) exchanging NaY zeolite serving as a raw material with an ammonium chloride solution, wherein the treatment conditions are as follows: according to NaY molecular sieve (dry basis): ammonium chloride: water 1: 0.7: 10, exchange at 85 ℃ for 1h, filter, wash with deionized water, and dry at 120 ℃ for 4 h.

(2) And (2) carrying out first hydrothermal roasting treatment on the molecular sieve obtained in the step (1), wherein the roasting temperature is 600 ℃, and roasting for 2h in a 100% steam atmosphere.

(3) And (3) mixing the molecular sieve obtained in the step (2) according to the mass ratio of the molecular sieve (dry basis): citric acid: sulfuric acid: water 1: 0.15: 0.05: and 8, adding water into the molecular sieve, pulping, heating, adding 20% sulfuric acid at a constant speed at 70 ℃ under stirring, controlling the dropping time for 30min, adding 20% citric acid aqueous solution, controlling the dropping time for 20min, continuously stirring at 70 ℃ for 1h after the addition is finished, filtering, washing with deionized water, and drying at 120 ℃ for 4 h.

(4) And (4) carrying out second hydrothermal roasting treatment on the molecular sieve obtained in the step (3), wherein the roasting temperature is 600 ℃, and roasting for 2 hours in a 100% steam atmosphere.

(5) And (3) mixing the molecular sieve obtained in the step (4) according to the mass ratio of the molecular sieve (dry basis): hydrochloric acid: oxalic acid: ammonium sulfate: water 1: 0.05: 0.19: 0.1: 10, adding water into the molecular sieve, pulping, adding ammonium sulfate, slowly dripping hydrochloric acid with the concentration of 10%, controlling the dripping time for 40min, adding oxalic acid, heating, treating at 70 ℃ for 60min, filtering, and washing with deionized water.

(6) Sieving the molecular sieve obtained in the step (5) according to a molecular sieve; ammonium chloride: fluosilicic acid, hydrochloric acid: h₂Adding water into the molecular sieve for pulping, adding ammonium chloride, slowly dropwise adding 30% fluosilicic acid and 20% hydrochloric acid at the same time, controlling the dropwise adding time for 60min, heating, treating at 60 ℃ for 50min, filtering, and washing with deionized water to obtain the molecular sieve D-3, wherein each parameter is shown in Table 1.

Comparative example 4

Compared with the preparation process of the example 3, the step 8 is omitted and the step 7 is repeated for 2 times, namely, the final dealumination treatment process does not adopt a silicon-containing dealumination agent, and the specific steps are as follows:

(1) exchanging NaY zeolite serving as a raw material with an ammonium chloride solution, wherein the treatment conditions are as follows: according to NaY molecular sieve (dry basis): ammonium chloride: water 1: 0.7: 10, exchange at 85 ℃ for 1h, filter, wash with deionized water, and dry at 120 ℃ for 4 h.

(2) And (2) carrying out first hydrothermal roasting treatment on the molecular sieve obtained in the step (1), wherein the roasting temperature is 600 ℃, and roasting for 2h in a 100% steam atmosphere.

(3) And (3) mixing the molecular sieve obtained in the step (2) according to the mass ratio of the molecular sieve (dry basis): citric acid: sulfuric acid: water 1: 0.15: 0.05: and 8, adding water into the molecular sieve, pulping, heating, adding 20% sulfuric acid at a constant speed at 70 ℃ under stirring, controlling the dropping time for 30min, adding 20% citric acid aqueous solution, controlling the dropping time for 20min, continuously stirring at 70 ℃ for 1h after the addition is finished, filtering, washing with deionized water, and drying at 120 ℃ for 4 h.

(4) And (4) carrying out second hydrothermal roasting treatment on the molecular sieve obtained in the step (3), wherein the roasting temperature is 600 ℃, and roasting for 2 hours in a 100% steam atmosphere.

(5) And (3) mixing the molecular sieve obtained in the step (4) according to the mass ratio of the molecular sieve (dry basis): hydrochloric acid: ammonium sulfate: water 1: 0.06: 0.1: 10, adding water into the molecular sieve, pulping, adding ammonium sulfate, stirring uniformly, slowly dropwise adding hydrochloric acid with the concentration of 15%, controlling the dropwise adding time to be 1h, heating to 60 ℃, treating for 40min, filtering, washing with deionized water, and drying at 120 ℃ for 4 h.

(6) And (4) carrying out third hydrothermal roasting treatment on the molecular sieve obtained in the step (5), wherein the roasting temperature is 550 ℃, and roasting for 3 hours in a 100% water vapor atmosphere.

(7) And (3) mixing the molecular sieve obtained in the step (6) according to the mass ratio of the molecular sieve (dry basis): hydrochloric acid: oxalic acid: ammonium sulfate: water 1: 0.05: 0.19: 0.1: 10, adding water into the molecular sieve, pulping, adding ammonium sulfate, slowly dripping hydrochloric acid with the concentration of 10%, controlling the dripping time for 40min, adding oxalic acid, heating, treating at 70 ℃ for 60min, filtering, and washing with deionized water.

(8) And (3) mixing the molecular sieve obtained in the step (7) according to the mass ratio of the molecular sieve (dry basis): hydrochloric acid: oxalic acid: ammonium sulfate: water 1: 0.05: 0.19: 0.1: 10, adding water into the molecular sieve, pulping, adding ammonium sulfate, slowly adding hydrochloric acid with the concentration of 10% dropwise, controlling the dropwise adding time to be 40min, adding oxalic acid, heating, treating at 70 ℃ for 60min, filtering, and washing with deionized water to obtain the molecular sieve D-4, wherein all parameters are shown in table 1.

Comparative example 5

Compared with the preparation process of the example 3, the step 8 is omitted, and the specific steps are as follows:

(1) exchanging NaY zeolite serving as a raw material with an ammonium chloride solution, wherein the treatment conditions are as follows: according to NaY molecular sieve (dry basis): ammonium chloride: water 1: 0.7: 10, exchange at 85 ℃ for 1h, filter, wash with deionized water, and dry at 120 ℃ for 4 h.

(2) And (2) carrying out first hydrothermal roasting treatment on the molecular sieve obtained in the step (1), wherein the roasting temperature is 600 ℃, and roasting for 2h in a 100% steam atmosphere.

(3) And (3) mixing the molecular sieve obtained in the step (2) according to the mass ratio of the molecular sieve (dry basis): citric acid: sulfuric acid: water 1: 0.15: 0.05: and 8, adding water into the molecular sieve, pulping, heating, adding 20% sulfuric acid at a constant speed at 70 ℃ under stirring, controlling the dropping time for 30min, adding 20% citric acid aqueous solution, controlling the dropping time for 20min, continuously stirring at 70 ℃ for 1h after the addition is finished, filtering, washing with deionized water, and drying at 120 ℃ for 4 h.

(4) And (4) carrying out second hydrothermal roasting treatment on the molecular sieve obtained in the step (3), wherein the roasting temperature is 600 ℃, and roasting for 2 hours in a 100% steam atmosphere.

(5) And (3) mixing the molecular sieve obtained in the step (4) according to the mass ratio of the molecular sieve (dry basis): hydrochloric acid: ammonium sulfate: water 1: 0.06: 0.1: 10, adding water into the molecular sieve, pulping, adding ammonium sulfate, stirring uniformly, slowly dropwise adding hydrochloric acid with the concentration of 15%, controlling the dropwise adding time to be 1h, heating to 60 ℃, treating for 40min, filtering, washing with deionized water, and drying at 120 ℃ for 4 h.

(6) And (4) carrying out third hydrothermal roasting treatment on the molecular sieve obtained in the step (5), wherein the roasting temperature is 550 ℃, and roasting for 3 hours in a 100% water vapor atmosphere.

(7) And (3) mixing the molecular sieve obtained in the step (6) according to the mass ratio of the molecular sieve (dry basis): hydrochloric acid: oxalic acid: ammonium sulfate: water 1: 0.05: 0.19: 0.1: 10, adding water into the molecular sieve, pulping, adding ammonium sulfate, slowly adding hydrochloric acid with the concentration of 10% dropwise, controlling the dropwise adding time to be 40min, adding oxalic acid, heating, treating at 70 ℃ for 60min, filtering, and washing with deionized water to obtain the molecular sieve D-5, wherein all parameters are shown in table 1.

Comparative example 6

Compared with the preparation process of example 3, step 7 is omitted, and the details are as follows:

(1) exchanging NaY zeolite serving as a raw material with an ammonium chloride solution, wherein the treatment conditions are as follows: according to NaY molecular sieve (dry basis): ammonium chloride: water 1: 0.7: 10, exchange at 85 ℃ for 1h, filter, wash with deionized water, and dry at 120 ℃ for 4 h.

(2) And (2) carrying out first hydrothermal roasting treatment on the molecular sieve obtained in the step (1), wherein the roasting temperature is 600 ℃, and roasting for 2h in a 100% steam atmosphere.

(3) And (3) mixing the molecular sieve obtained in the step (2) according to the mass ratio of the molecular sieve (dry basis): citric acid: sulfuric acid: water 1: 0.15: 0.05: and 8, adding water into the molecular sieve, pulping, heating, adding 20% sulfuric acid at a constant speed at 70 ℃ under stirring, controlling the dropping time for 30min, adding 20% citric acid aqueous solution, controlling the dropping time for 20min, continuously stirring at 70 ℃ for 1h after the addition is finished, filtering, washing with deionized water, and drying at 120 ℃ for 4 h.

(4) And (4) carrying out second hydrothermal roasting treatment on the molecular sieve obtained in the step (3), wherein the roasting temperature is 600 ℃, and roasting for 2 hours in a 100% steam atmosphere.

(5) And (3) mixing the molecular sieve obtained in the step (4) according to the mass ratio of the molecular sieve (dry basis): hydrochloric acid: ammonium sulfate: water 1: 0.06: 0.1: 10, adding water into the molecular sieve, pulping, adding ammonium sulfate, stirring uniformly, slowly dropwise adding hydrochloric acid with the concentration of 15%, controlling the dropwise adding time to be 1h, heating to 60 ℃, treating for 40min, filtering, washing with deionized water, and drying at 120 ℃ for 4 h.

(6) And (4) carrying out third hydrothermal roasting treatment on the molecular sieve obtained in the step (5), wherein the roasting temperature is 550 ℃, and roasting for 3 hours in a 100% water vapor atmosphere.

(7) The molecular sieve obtained in the step (6) is treated according to a molecular sieve (dry basis); ammonium chloride: fluosilicic acid, hydrochloric acid: h₂Adding water into the molecular sieve for pulping, adding ammonium chloride, slowly dropwise adding 30% fluosilicic acid and 20% hydrochloric acid at the same time, controlling the dropwise adding time for 60min, heating, treating at 60 ℃ for 50min, filtering, and washing with deionized water to obtain the molecular sieve D-6, wherein each parameter is shown in table 1.

TABLE 1 parameters of molecular sieves in examples and comparative examples

Note: the non-framework aluminum ratio in Table 1 is the ratio of the area of the peak of the formant signal with a chemical shift of 0. + -.2 ppm to the total area of the peak.

Application example

The molecular sieves obtained in examples 1-4 and comparative examples 1-6 are impregnated with a solution of ammonium tetrathiomolybdate to prepare catalysts, which specifically comprises the following steps:

weighing 128.6 g of pseudoboehmite (catalyst Changling division) with a dry basis of 70% and 134.1 g of molecular sieve with a dry basis of 82%, uniformly mixing, extruding into a three-leaf bar shape with the diameter of 1.6 mm on a strip extruder, drying for 3 hours at 120 ℃, and roasting for 4 hours at 600 ℃ to obtain a catalyst carrier;

taking 100 g of catalyst carrier, and using 82 ml of MoS-containing catalyst carrier₂339.0 g/l ammonium tetrathiomolybdate solution, soaking for 3 hr at 120 deg.C, and N₂Drying for 6 hours in the atmosphere, and then roasting for 3 hours at 450 ℃ to obtain the catalyst.

And (4) carrying out hydrocracking reaction performance evaluation on the catalyst.

The performance evaluation of the hydrocracking reaction is finished by a pure hydrocarbon micro-reactor, and is carried out by adopting an ASTM D5154-2010 standard method; the raw material oil is tetrahydronaphthalene, the reaction pressure is 4.0MPa, the reaction temperature is 370 ℃, and the space velocity is 6.0h^-1The selectivity of the product to the ring-opened product in the reaction product is the yield of the monocyclic aromatic hydrocarbon product/conversion x 100%.

The prepared catalyst needs to be subjected to supplementary presulfurization before reaction under the condition that the temperature is 330 ℃ and the sulfur oil is 6 percent CS₂And (5) cyclohexane, wherein the vulcanization time is 1h, then the reaction oil is switched to, the temperature is increased to 370 ℃, and the sample is taken after the reaction temperature is stabilized for 2.5 h. In order to determine the stability of the catalyst, the temperature is gradually raised to 380 ℃ and 390 ℃ after sampling, then the temperature is raised to 380 ℃, and the temperature loss when the temperature is raised to 380 ℃ is calculated according to the conversion rate; it is generally accepted that the smaller the temperature loss, the better the stability of the catalyst activity. The reactivity of the finally obtained catalyst is shown in Table 2.

TABLE 2 reactivity of catalysts made from the molecular sieves of the examples and comparative examples

The test results in Table 2 show that, compared with the molecular sieves of comparative examples 1-6, the molecular sieves of examples 1-4 of the present invention have higher reactivity, less secondary reactions, good ring-opening reaction selectivity, good acid stability and slow deactivation in hydrocracking reactions.

It should be noted by those skilled in the art that the described embodiments of the present invention are merely exemplary and that various other substitutions, alterations, and modifications may be made within the scope of the present invention. Accordingly, the present invention is not limited to the above-described embodiments, but is only limited by the claims.